This invention relates to switched capacitor circuits or networks and more particularly to a switched capacitor circuit replacement for a source resistor.
There is currently much interest in the simulation of resistors with switched capacitor circuits so that filters and networks can be implemented in fully integrated circuit form. A switched capacitor circuit that is particularly useful for simulating a source resistor in a direct ladder filter is described in "Improvement Circuit Elements for Switched-Capacitor Ladder Filters" by Man Shek Lee, Electronics Letters, Feb. 14, 1980, Vol. 16, No. 4, Pages 131-133. The simulation circuit there requires a voltage follower and is sensitive to top plate parasitic capacitance effects.
An object of this invention is the provision of a switched capacitor source resistor that is particularly useful in a multiple feedback ladder simulation circuit.